1. Field of the Invention
The invention relates to a panel structure of a plasma display panel.
2. Description of the Related Art
Recent years, a surface discharge scheme AC type plasma display panel as an oversized and slim display for color screen has been received attention, which is becoming widely available.
FIG. 10 is a schematic front view of a conventional surface discharge scheme AC type plasma display panel. FIG. 11 is a sectional view taken along the V3xe2x80x94V3 line of FIG. 10. FIG. 12 is a sectional view taken along the W4xe2x80x94W4 line of FIG. 10. FIG. 13 is a sectional view taken along the W5xe2x80x94W5 line of FIG. 10.
In FIG. 10 to FIG. 13, on the backside of a front glass substrate 1 to serve as a display screen of the plasma display panel, there is sequentially provided with a plurality of row electrode pairs (Xxe2x80x2, Yxe2x80x2); a dielectric layer 2 overlaying the row electrode pairs (Xxe2x80x2, Yxe2x80x2); and a protective layer 3 made of MgO which overlays a backside of the dielectric layer 2.
The row electrodes Xxe2x80x2 and Yxe2x80x2 respectively consist of wider transparent electrodes Xaxe2x80x2 and Yaxe2x80x2 each formed of a transparent conductive film made of ITO (Indium Tin Oxide) or the like, and narrower bus electrodes Xbxe2x80x2 and Ybxe2x80x2 each formed of a metal film, complementary to conductivity of the transparent electrode.
The row electrodes Xxe2x80x2 and Yxe2x80x2 are arranged opposing each other with a discharge gap gxe2x80x2 interposed between them, and alternate in the column direction. Each row electrode pair (Xxe2x80x2, Yxe2x80x2) forms a display line (row) L for matrix display.
A back glass substrate 4 faces the front glass substrate 1 with a discharge space Sxe2x80x2, filled with a discharge gas, in between. The back glass substrate 4 is provided with a plurality of column electrodes Dxe2x80x2 arranged to extend in a direction perpendicular to the row electrode pairs Xxe2x80x2 and Yxe2x80x2; band-shaped partition walls 5 each extending between the adjacent column electrodes Dxe2x80x2 in parallel; and a phosphor layer 6 consisting of a red phosphor layer 6(R), green phosphor layer 6(G) and blue phosphor layer 6(B) and overlaying side faces of the partition walls 5 and the column electrodes Dxe2x80x2.
In each display line L, the column electrodes Dxe2x80x2 and the row electrode pair (Xxe2x80x2, Yxe2x80x2) cross each other and the partition walls 5 divide the discharge space Sxe2x80x2, to form a unit light emitting area, and thus a discharge cells Cxe2x80x2 is defined therein.
In the plasma display panel, as illustrated in FIGS. 11 and 12, on the backside of the dielectric layer 2 and at a portion opposing to the bus electrodes Xbxe2x80x2 and Ybxe2x80x2 oriented back to back and extending in parallel, an additional dielectric layer 2A is formed to extend along the bus electrodes Xbxe2x80x2 and Ybxe2x80x2 in parallel.
The additional dielectric layer 2A is formed to protrude from the backside of the dielectric layer 2 into the discharge space Sxe2x80x2. The additional dielectric layer 2A has the function of limiting the spread of a surface discharge d caused between the opposite transparent electrodes Xaxe2x80x2 and Yaxe2x80x2 in the discharge space Sxe2x80x2 from going toward the bus electrodes Xbxe2x80x2 and Ybxe2x80x2 so as to prevent occurrence of a false discharge between the discharge cells Cxe2x80x2 adjacent to each other in the column direction.
In the above surface discharge scheme AC type plasma display panel, an image is displayed as follows:
First, through addressing operation, discharge (opposite discharge) is caused selectively between the row electrode pairs (Xxe2x80x2, Yxe2x80x2) and the column electrodes Dxe2x80x2 in the respective discharge cells Cxe2x80x2, to scatter lighted cells (the discharge cell in which wall charge is formed on the dielectric layer 2) and nonlighted cells (the discharge cell in which wall charge is not formed on the dielectric layer 2), over the panel in accordance with the image to be displayed.
After the address operation, in all the display lines L, the discharge sustain pulse is applied alternately to the row electrode pairs (Xxe2x80x2, Yxe2x80x2) in unison. In each lighted cell, for every application of the discharge sustaining pulse, surface discharge is produced in each space between a pair of additional dielectric layers 2A adjacent to each other sandwiching the lighted cell. The above surface discharge generates ultraviolet radiation, and thus the corresponding red(R), green (G) and/or blue (B) phosphor layers 6 in the discharge space Sxe2x80x2 are excited to emit light, resulting in forming the display image.
As explained above, in the conventional plasma display panel (PDP), the additional dielectric layer 2A formed in the portion facing the bus electrodes Xbxe2x80x2, Ybxe2x80x2 to extend in the row direction, limits the spreading of the discharge in the column direction in order to prevent occurrence of interference between discharges in the adjacent discharge cells Cxe2x80x2 in the column direction.
However, as shown in FIG. 13, the conventional PDP has a clearance rxe2x80x2 which is formed between the partition wall 5 and the dielectric layer 2 and between the adjacent discharge cells Cxe2x80x2 in the row direction in order to feed and exhaust a discharge gas into and from the discharge cells Cxe2x80x2. For this reason, as illustrated in FIG. 10, the surface discharge d in one discharge cell may spread via the clearance rxe2x80x2 into an adjacent discharge cell Cxe2x80x2 in the row direction, to possibly cause interfering discharges.
Although the spread of the discharge in the column direction is passably limited by the additional dielectric layer 2A as explained above, if the surface discharge d develops beyond the additional dielectric layer 2A, it is impossible to completely prevent the interference between the discharges in the adjacent discharge cells Cxe2x80x2 in the column direction.
The possibility of such interference between the discharges in the row direction and the column direction increases, as a pitch between the discharge cells decreases in relation to the high definition of an image. In the event of interfering discharges, lighted and unlighted discharge cells may be reversed producing an instable and inaccurate image.
The present invention has been made to solve the above problems associated with the conventional plasma display panel.
It is therefore an object of the present invention to provide a plasma display panel which is capable of effectively preventing interference between discharge in adjoining discharge cells to display a stable image.
To attain the above object, a plasma display panel according to a first invention includes a plurality of row electrode pairs extending in a row direction and arranged in a column direction to respectively form display lines and a dielectric layer overlaying the row electrode pairs on a backside of a front substrate, and a plurality of column electrodes extending in the column direction and arranged in the row direction on a back substrate facing the front substrate via a discharge space, and unit light emitting areas formed to be partitioned by a partition wall having at least vertical walls extending in the column direction in a discharge space corresponding to each intersection of the column electrode and the row electrode pair. Such plasma display panel features in that a floating electrode is provided on each portion of at least one of the front substrate and the back substrate facing the vertical wall of the partition wall partitioning the adjacent unit light emitting areas from each other in the row direction.
In the plasma display panel according to the first invention, for forming an image, when a surface discharge is caused between the transparent electrodes of the row electrode pair opposing each other in each unit light emitting area, and then the surface discharge caused around the gap between a pair of the transparent electrodes is moving to another pair of the transparent electrode in an adjacent unit light emitting area in the row direction, the surface discharge is attracted by the floating electrode provided to face the vertical wall of the partition wall partitioning the adjacent unit light emitting areas from each other in the row direction. This does not allow the surface discharge to reach another transparent electrode in an adjacent unit light emitting area.
According to the first invention, therefore, the spread of the surface discharge into an adjacent unit light emitting area in the row direction is limited and occurrence of interference between discharges in the adjacent unit light emitting areas is prevented, resulting in displaying stable images.
To attain the aforementioned object, a plasma display panel according to a second invention features, in addition to the configuration of the first invention, in that the floating electrode is formed of a transparent conductive film or a metal film.
According to the plasma display panel of the second invention, by reason of forming the floating electrode of a transparent conductive film or a metal film, when the surface discharge is caused between the adjacent light emitting areas in the row direction of the plasma display panel, in forming an image, then is scattering to an adjacent unit light emitting area, the floating electrode provided between the two unit light emitting electrodes attracts the surface discharge. Therefore, the surface discharge cannot reach the inside of an adjacent unit light emitting area, and interference of discharges is prevented between the adjacent unit light emitting areas in the row direction.
To attain the aforementioned object, a plasma display panel according to a third invention features, in addition to the configuration of the first invention, in that each of the transparent electrodes of the row electrode pair opposing each other via a predetermined gap is formed in an independent island-like form in each unit light emitting area, and the floating electrode is placed in a position between distal ends of the transparent electrodes in the two unit light emitting areas adjacent to each other in the row direction or a position facing the position between the distal ends of the transparent electrodes in the two adjacent unit light emitting areas.
According to the plasma display panel of the third invention, in the plasma display panel in which the transparent electrodes of the row electrode pair opposing each other with a predetermined gap in between are formed in an independent island-like form for each unit light emitting area, the floating electrode is placed in a position between the distal ends of the respective transparent electrodes in the two unit light emitting areas adjacent to each other in the row direction. As a result, it is possible to effectively prevent discharge from interfering with another unit light emitting area in the distal portions of the transparent electrodes in which the surface discharge is caused most frequently.
To attain the aforementioned object, a plasma display panel according to a fourth invention features, in addition to the configuration of the third invention, in that the floating electrode extends from a position opposing a distal portion of one of a pair of the transparent electrodes to a position opposing a distal portion of the other transparent electrode.
According to the plasma display panel of the fourth invention, between the two unit light emitting areas adjacent to each other in the row direction, the floating electrode is interposed between the opposing distal portions of respective one of the adjacent pair of transparent electrodes, between the opposing distal portions of the other, and between the opposing gaps formed between each pair of transparent electrodes. This configuration can further advantageously block the scattering of the surface discharge between the two adjacent unit light emitting areas, resulting in preventing occurrence interference between discharges.
To attain the aforementioned object, a plasma display panel according to a fifth invention features, in addition to the configuration of the first invention, in that the floating electrode has a widthwise extended portion integrated with a main body extending along the vertical wall of the partition wall facing the main body, and extending in a direction perpendicular to the vertical wall.
According to the plasma display panel of the fifth invention, a widthwise extended portion extending in a direction perpendicular to the vertical wall of the partition walls, namely a direction at right angles to the main body of the floating electrode, prevents the main body formed in the floating electrode to have a smaller width because it faces the vertical wall of the partition wall, from separating from the front substrate or the back substrate.
These and other objects and features of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings.